Allow computer in remote location to only connect via VPN?

I am looking to setting up a computer in a remote location.

All I want that computer to be able to do is to use remote desktop to connect via the internet to my sonicwall VPN. I do not want them to have any other web access. At all.
I also have to block them from taking a different computer and plugging it in, to use the internet connection for other purposes.

Any suggestions?

Thank You